Put a bell on toddlers' belts to more easily locate them
From Will, Hedra's husband!
When your toddlers start to walk around, it can be tiring to track their presence at all times, especially in crowded areas, or in the outdoors. When we had this situation while on vacation in Vermont, we bought a souvenir cowbell for Brendan that he loved to wear, and that let us know where he was at all times. And most importantly, let us know when he stopped moving.
When the girls started walking we bought them bells too, making sure that 1) they are nice sounding, and 2) they sounded different. We made a loop of elastic and hung the bells on that with mini-carabineer clips. They love their bells, eagerly letting us put them on, because they make a nice sound and we let them run around with more freedom when they have the bells. When they don't want the bells, the rule is "bell or hold my hand".
1) While they get to roam more freely, we're not talking racing off miles ahead. Just 'longer than arms reach' up to a reasonable distance for parental leaping-to-the-rescue depending on conditions. Mainly this is 'retractable dog-leash' distances - fairly close most of the time, some capacity to roam more if appropriate.
2) You can also tell speed and type of movement by the cadence of the ringing. Ding ... ding ... ding... (walking) or ding-ding-ding-ding! (running) or DING-ding-DING-ding (hopping) or ding-ding-CLATTER-silence (tripping and falling) or ding-ding-ding ... ding ... ... ding ... silence (distracted by shiny object or animal or general forbidden items).
3) Bonus, kids like to make loud noises. Here's one that's allowed! (Big tip - pick a bell that doesn't make you wince when it rings)
4) Cow bells, turkey bells (like cow bells but smaller), and brass bells (like the Indian and other 'asian' bells you can get for door chimes) all should work well. Smaller jingle bells aren't loud enough (big ones may be, but might not ring on every step). Something that swings a bit with every stride is good (hence the carabineers, also).
5) Great for camping or other situations where you might look away or be blocked from sight for a moment in normal play (I hate that instant panic when the child vanishes when you glance away and back again!). Or where they could get distracted by something cool and just walk in a different direction while you're pulling out the money for the ice cream cone. Zoos, parks, parades (if not overly noisy), rest areas, botanical gardens, some museums, family reunions, birthday parties for older siblings, smaller out-door music events, etc,